This spacecraft, of the Ye-2A class, was the first Soviet probe designed to take pictures of the far side of the moon using the Yenisey-2 imaging system (replacing the Yenisey-1 used on the abandoned Ye-2 probe).

The TV system consisted of a 35-mm camera with two lenses of 200-mm (wide-angle) and 500-mm (high-resolution) focal lengths and a capacity to read up to 40 images. Strictly speaking, the probe was not meant to reach escape velocity; instead, the launch vehicle inserted the spacecraft, called the Automatic Interplanetary Station (AMS) in the Soviet press, into a highly elliptical orbit around the Earth at 48,280 x 468,300 kilometers, sufficient to reach lunar distance.

During the coast to the moon, the AMS suffered overheating problems and poor communications, but the vehicle eventually passed over the moon's southern polar cap at a range of 7,900 kilometers on 6 October before climbing up over the Earth-moon plane.

At a distance of 65,200 kilometers from the moon, on 7 October, cameras began taking the first of 29 pictures of the far side of the moon. The exposed film was then developed, fixed, and dried automatically, after which a special light beam of up to 1,000 lines per image scanned the film for transmission to Earth.

Images were finally received the next day (after a few aborted attempts). Seventeen of the images were of usable quality and showed parts of the moon never before seen by human eyes. The spacecraft, named Luna 3 after 1963, photographed about 70 percent of the far side and found fewer mare areas on the far side, prompting scientists to revise their theories of lunar evolution.

Key Dates

4 Oct 1959: Launch

7 Oct 1959: First Lunar Photographs Taken

Status: Successful

Fast Facts

Seventeen of Luna 3's 29 images were usable.

Luna 3's images covered 70 percent of surface of the lunar far side. They were used to create the first rudimentary atlas.

The images prompted scientists to revise their theories of lunar evolution.

Seventeen of Luna 3's 29 photos of the far side of the moon (right) were usable.

The photos were developed, fixed and dried on the spacecraft and beamed back to Earth.

The moon takes about 29 days to orbit the Earth, roughly the same amount of time to make one rotation on its axis. That is why we always see the same side of the moon from Earth.